The ornamental design for a sleepdiagnosticdevice, as shown and described.
FIG. 1 is a front perspective view of the claimed sleep diagnostic device;
FIG. 2 is a back perspective view thereof;
FIG. 3 is a front orthogonal view thereof;
FIG. 4 is a back orthogonal view thereof;
FIG. 5 is a top orthogonal view thereof;
FIG. 6 is a bottom orthogonal view thereof;
FIG. 7 is a right side orthogonal view thereof; and,
FIG. 8 is a left side orthogonal view thereof.
Regularly broken lines in the drawings are included for the purpose of illustrating unclaimed portions of the sleep diagnostic device and form no part of the claimed design. Lines with random slight breaks are intended to show smooth contours, as opposed to solid lines which show sharp edges.